GALLIC ACID 421 



gr.x-xx, (.6-1.8), on food. Tannocol is a gelatine precipitate and is identical in 

 uses and doses. 



Tannigen, Tannyl AcetatEj CijHwOu- 

 Made by heating tannin and acetic anhydride in the presence of glacial acetic 

 acid. Occurs as a light gray, odorless, tasteless powder. Insoluble in water but 

 soluble in alcohol and alkalies. It passes unchanged through the stomach into 

 the bowels where it acts as an astringent in the presence of the solvent action of 

 the alkaline juices. It is useful in diarrhea and dysentery in young animals. 

 Foals and calves take gr.xxx, (2), with food. The advantage of both of these 

 preparations over tannic acid depends upon the fact that they do not irritate the 

 stomach, passing through it unchanged, and being only dissolved by the alkaline 

 intestinal juices. Tannoform, a combination of tannin and with formaldehyde, 

 and tannopin, the union of tannin with hexamethylenamine ; are yellow, odorless 

 and tasteless powders used for tiie same purposes and in the same doses as tan- 

 nigen and tannalbin. The latter are astringent and antiseptic dusting powders 

 externally. 



AciDUM Galmcum. Gallic Acid. C,H805+HjO. (U, S. & B. P.) 



Synonym. — Acide gallique, Fr. ; gallussilure, G. 



An organic acid, usually prepared from tannic acid. 



Derivation. — Made by exposure of paste of nutgall and water to the air for 

 a month, when tannic acid undergoes hydration (tannic acid) HCuH80„ + HjO=: 

 2 HC7H5O5 (gallic acid). The liquid is then expressed from the paste and the 

 residue is boiled with distilled water and filtered, when hot, through animal 

 charcoal. Gallic acid crystallizes out from the filtrate. 



Properties. — White, or pale fawn-colored, silky, interlaced needles or tri- 

 clinic prisms; odorless; having an astringent or slightly acidulous taste; perma- 

 nent in the air. Soluble in 87 parts of water, and in 4.6 parts of alcohol; in 100 

 parts of ether, and in 10 parts of glycerin. 



Incompatibles. — Metallic salts and spirit of nitrous ether. 



Dose.—H. & C, 3ii-Sss, (8-15); Sh. & Sw., 3ss-i, (2-4); D., gr.v-xx, (.3-1.8). 



Action and Uses. — Experiments show that gallic acid has a very 

 feeble astringent action when locally applied and tannic acid should 

 always be preferred. It is absorbed and transformed into sodium gallate 

 and exists in this form in the tissues. 



Since sodium gallate has no remote astringent action its use by the 

 mouth for such a purpose is without scientific basis, although successful 

 results are alleged to have followed its administration in the treatment of 

 hemorrhage from the lungs, uterus and kidneys, and in polyuria, albumin- 

 uria, bronchorrhea, leukorrhea, and excessive sweating. 



Pyrogallol. Pyrogallol. C„H3(OH)3. (U. S. P.) 



Synonym. — Pyrogallic acid. 



Derivation. — Trihydroxy benzene obtained chiefly by the dry distillation of 

 gallic acid, C,Hs05=:C„H3(OH)3-|-C02. 



Properties. — Light, white, or nearly white, laminae, or fine needles; odorless, 

 and having a bitter taste; acquiring a grayish tint on exposure to air and light. 

 Soluble in 1.7 parts of water, and in 1.3 parts of alcohol; also soluble in 1.6 parts 

 of ether. 



Action and Uses. — Pyrogallol is an excellent agent for the treatment 

 of chronic psoriasis and for ringworm. An ointment containing an 

 amount of pyrogallol varying from gr.x-3i to the .ounce of lard, is 

 commonly employed. Toxic symptoms may follow its extensive applica- 

 tion. 



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